I've planned all along to have a DC only teardrop. For my needs it is the ideal situation. (and I won't have to face the dreaded NEC)

I've always thought I could just use a generator to keep the battery topped of during the trip. First off, most generators are too large, heavy and too expensive for such a small need. Then I read about the Power Pony generator. Sounded like a neat comprimise.............but, alas, it has been discontinued.........as have all other super small generators I've searched for. Months ago I read about keeping the battery topped of with the tow vehicle's alternating system. Simple enough. However, further reading on the internet indicates that a true deep cycle battery will actually be damaged by being charged with an automotive generator with a voltage regulator. Seems it will charge too quickly and burn out the cells. Works great for a "starter" type battery, but not deep cycle. I've even thought about using a voltage converter attached to the tow vehicle's charging system to power a regular battery charger while the vehicle is in operation, but I'm not quite certain that would work effectively.

So my question is this: How do I use the tow vehicle's charging system to safely charge my expensive deep cycle battery?

Chris

The tension between what is good enough and what is beyond that creates the space for character to become our work.

The battery that I am charging with the solar panel, in the Tab, is a cheap Interstate Deep Cycle battery.

For my teardrop I haven't bought the battery yet, but will probably get an Optima if I can find it, or a Hawker! Or if I'm feeling a little bit cheaper, I'll get the biggest deep cycle battery I can find at Walmart!

Mike...

The quality is remembered long after the price is forgotten, so build your teardrop with the best materials...

Mike, I have a friend who sells Optima batteries so I plan to buy one of their deep cycle batteries...........not the deep cycle marine battery, but a true deep cycle. I don't really know the difference, but seems there is one. As far as a solar panel, firstly they are pretty darned expensive, and second I spend most of my camping experiences in deep woods. Wouldn't it be hard to depend on only daylight hours on the open road to keep my battery topped off? If I'm hooked to the tow vehicle, I can recharge the battery on the darkest of days or situations.

Chris

The tension between what is good enough and what is beyond that creates the space for character to become our work.

Then you almost have to get a 1000 watt Honda or Yahama generator. You'll run it for an hour or two in the morning to top off your battery.

I'm using the solar panel in the back yard, where the trailer is in the sun all day long. If you had a site that was partly in the sun and partly in the shade you could move the solar panel around to catch the sun. But in total shade, you are right, the solar panel won't help much.

I have been thinking about this energy problem for a couple years now, and I still have not found a good answer.

I thought solar was it, but in some cases it's not the answer. I thought a 1000 watt generator was the answer but it's pretty expensive, and you have to carry gas around with you too. But it's looking to be the best alternative if you are off the grid.

Q is off the grid, and he has a lot of experience with solar and generators. I know he has a solar panel on his teardrop. I wonder if he has a generator he uses for his teardrop?

Mike...

The quality is remembered long after the price is forgotten, so build your teardrop with the best materials...

I can't see the expense of the Honda generator................or the weight, space loss, and fuel requirements. Surely there is a good way to do this with the tow vehicle's charging system......i.e. some way to regulate the voltage and amperage so as not to damage the battery. Hmmm. Someone in our group must surely know how to handle this problem. Plenty of "juice chasers" out there. (and I don't mean Crown and pickle juice) One of them has to know.

Chris

The tension between what is good enough and what is beyond that creates the space for character to become our work.

So my question is this: How do I use the tow vehicle's charging system to safely charge my expensive deep cycle battery?

Chris,

To get back to your original question, if you want to regulate the charge current from your vehicle's alternator, put some light bulbs in series with the battery. The light bulbs will reduce the voltage to the battery reducing the charge current to a level of your choosing, by choosing the size/type of 12volt light bulbs.

I'm not a fan of Optima batteries. IMHO they are vastly over rated and don't hold up as well as a good quality conventional design. Your cheapest, easiest, and best solution is to get a conventional RV battery and charge it directly from the alternator, with an isolator.

Optima batteries are made by Johnson Controls, who used to make all Sears batteries. In the mid 80s they came out with a similar battery that they called the Incredicell. Smaller in size and lighter in weight than conventional batteries, thin plates with fiberglass mat seperators, lots of plate surface area, mucho cold cranking amps, very long warranty, high price, low cost to produce. Only problem was they had little reserve power, they didn't hold up well to heat and vibration, and most of them failed in a year or two. Sears replaced almost all of them under warranty. After that Sears dropped Johnson Controls as a supplier and went with Exide.

Q (former Sears Automotive Service Advisor)

Chris C wrote:Mike, I have a friend who sells Optima batteries so I plan to buy one of their deep cycle batteries...........not the deep cycle marine battery, but a true deep cycle. I don't really know the difference, but seems there is one. As far as a solar panel, firstly they are pretty darned expensive, and second I spend most of my camping experiences in deep woods. Wouldn't it be hard to depend on only daylight hours on the open road to keep my battery topped off? If I'm hooked to the tow vehicle, I can recharge the battery on the darkest of days or situations.

Q wrote:After that Sears dropped Johnson Controls as a supplier and went with Exide.

Q (former Sears Automotive Service Advisor)

Was that in the early/mid 90's? I remember a swap out on batteries back then, I never really knew why. I remember because I had to take my car, my mom's van, and my brother's car to get the battery swapped.

I live out in the country and about 8 out of 10 people out here use Optima batteries on their tractors, trucks and cars. Everyone I know says they work great.............if not better. Got a close friend up the road who put one on his tractor 15 years ago and says it's never failed to start, no matter the weather. On the other hand, I've had 3 Excide batteries in my 86' Dodge van since I bought it in 89'! They keep replacing them under warranty...... ........(or wait, they wouldn't replace the last one) but I've had nothing but trouble. Certainly wouldn't buy another. Guess one man's sugar is another's lemon.

Chris

The tension between what is good enough and what is beyond that creates the space for character to become our work.

A standard alternator cannot fully charge a battery, it rarely gets over 70% of fully charged, the reasons are long and very complex.

A true deep cycle battery cannot be damaged by the pathetic output of a standard alternator.

If you were to measure the voltage at the starter battery terminals you would see 13.8 to 14.2 Volts with the engine running, If you had a meter capable of showing the ampage going in, for a very short period you would see a good amount of amps going in, but within a minute if that it drops to a trickle.

Now if you were to stand your deep cycle battery xx Feet away and then run 2 wires to it, you would be suprised at the voltage drop, with the usual wire thicknesses people use you would be lucky only dropping .5volt.

The answer to suit you depends on, what you want to run (lights, TV or whatever) and how long you intend to stay on one spot without recharge.

The are many smart regulators for alternators available , these make a standard alternator into a fantastic 4 stage charger, capable of rapidly recharging all battery types. (around £100 UK)

If your needs are small power wise AND you want to stay on the same spot for a long time, then a solar panel could be the answer.

Proper Deep cycle batteries have big heavy plates, fork lift type batteries are true deep cycle, starter batteries have thinner but more numerous plates, this gives a greater surface area and aids getting power out quickly.

Unless you have major special needs, get a basic lead acid Leisure battery. I dont believe anyone can come up with a valid and supportable reason for any other type (Gel AGM Spiral cell etc)

Generator's for battery Charging, total waste of fuel, massively ineffecient. Building up a 12v version with a smart regulator, would be miles more efficient.